1. Field of the Invention
The present invention generally relates to a system and method for preserving, transporting, storing, re-hydrating and delivering viable micro-organisms. More particularly, the present invention is directed to a kit and method for preserving and storing dried, microbiological organisms and for re-hydrating and delivering specific and reproducible numbers of viable organisms, most preferably as a single, total dose of cells.
2. Description of the Background
The quantitative determination of the number of pathogenic and/or indicator micro-organisms in a sample is as important in many public health applications as the mere determination of the presence or absence of those organisms. The infective dose, i.e., the number of micro-organisms required to produce infection in the host, has been determined for many species. Although strain dependent, the infective dose may vary from as few as ten organisms of Shigella dysenteriae to as many as one hundred million or more for Salmonella typhosa or Vibrio cholerae.
In other applications, the wholesomeness or sanitary quality of food, milk, other dairy products, shellfish, potable water, shellfish growing waters, waste waters and a variety of surface waters is determined by the quantitative enumeration of specific indicator organisms.
The federal Food and Drug Administration (FDA) has equally stringent requirements and regulations controlling the microbial purity, i.e., sterility and effectiveness, of microbial preservatives in food, drugs, and cosmetics for human consumption and/or use.
There are many other applications in the clinical and veterinary fields for a product which provides specific and reproducible quantities of viable micro-organisms. For example, the Centers for Disease Control (CDC) in Atlanta, Ga. require both inhibition of quantitative challenge doses of saprophytic micro-organisms and recovery of quantitative doses of Neisseria gonorrhoeae and Neisseria meningitis by highly selective culture media such as Thayer Martin Agar and its modifications.
Federal and state statutes specifically provide precise requirements for methodology, equipment, facilities, quality assurance plans and quality control of analytical techniques, materials and individual analyst precision.
There has been a long felt but unfulfilled need in all the foregoing markets to evaluate the performance of techniques, materials and analysts using a product which will provide a specific and reproducible number of viable micro-organisms in a ready-for-use design.
While there are many commercial sources of standard micro-organisms available in viable states, there are no guarantees, implied or explicit, of the numbers of organisms present. Currently available methods for preserving micro-organisms have typically employed harsh conditions, e.g., vacuum lyophilization and storage at temperatures well below -20.degree. C. When subjected to these severe preservation and storage conditions no products have been capable of providing known and reproducible numbers of viable organisms. One attempt to solve this problem included the lyophilization of a specified count of cultures in a serum vial. Rehydration and transfer of the cultures in this vial required the use of a needle to dispense rehydration fluid followed by use of another needle and syringe to withdraw defined aliquots of solution to deliver a known count of cultures. The vial served as a reservoir and the system depended on the accuracy of the individual user to measure the rehydrating fluid, to properly mix the lyophilized culture and rehydrating fluid and to withdraw the defined aliquots. In addition to all of the possibilities for introduction of errors in this process, this method suffered from many opportunities for contamination of both the environment and the user resulting from the use of various needles, syringes or pipettes.
Because the foregoing sources have been unacceptable, the current state of the art for the aforementioned procedures requiring specific numbers of control micro-organisms has required on-site preparation of estimated doses of living micro-organisms. These processes require one or more transfers of the microbes, time for adequate growth to appear and subsequent preparation of a suspension containing an appropriate number of viable cells. There is no practical way to determine in advance the number of colony forming units. The process requires considerable skill, time and money to achieve and is as much art as science. These suspensions have relatively short shelf lives ranging from a few minutes to a maximum of 24 to 48 hours. Accordingly, there has been a long felt but unfulfilled need for a system of providing specific and reproducible numbers of viable micro-organisms in a safe and readily usable form.